Heretofore, a sputtering apparatus has been disclosed as shown in Japanese Patent Application Laid-Open No. 5-247639, in which multiple shields are provided between a target and a substrate holder for the purpose of preventing sputtering particles from adhering to an inner wall of a chamber. In such an apparatus, in order to control the pressure of a processing space partitioned by the target, the substrate holder, and the multiple shields, the conductance at a gap between the multiple shields has to be controlled by accurately positioning the multiple shields.
Meanwhile, the shields need to be replaced regularly when stained with a film adhering thereto. To facilitate this shield replacement work, an openable and closable top lid is provided to an upper portion of the apparatus in some cases. For example, Japanese Patent Application Laid-Open No. 2009-181972 discloses an MOCVD apparatus having: a gas-introducing port configured to introduce a film-forming gas into a reaction vessel; an openable and closable top lid configured to shut a top lid opening of the reaction vessel; an anti-adhesion plate (quartz plate) detachably provided on the top lid; and an elevating and rotating device configured to open or close the top lid and to adjust the angle of the top lid to a substrate.
Nevertheless, when the apparatus provided with an openable and closable top lid at its upper portion has a plasma space formed by a shield provided inside a chamber and a shield provided on the openable and closable top lid, the following problems are brought about. When the top lid of the chamber is closed in order to make the inside of the chamber airtight, a gap needs to be provided between the shield provided on the top lid and the shield provided inside the chamber. This is because that it is difficult to fabricate and machine precisely the shield provided on the top lid and the shield provided inside the chamber so that they contact each other exactly. Furthermore, they sometimes thermally expand during processing. When the top lid shield and the shield provided inside the chamber contact with each other, each shield can not thermally expand freely, so deformation and damage of the shield may be caused. On the other hand, when a large gap is designed in considering thermal expansion of the shields, sputtering particles may pass through the gap and directly adhere to an inner wall of the chamber. Hence, such a gap may work as a particle generation factor. Additionally, there is another problem that emission of a process gas to the outside of a processing space through this gap makes the internal pressure of the processing space unstable. An object of the present invention is to provide a substrate processing apparatus which allows the thermal expansion of the shields provided on the top lid of the chamber and inside the chamber, and which is enable to inhibit the sputtering particles to scatter out the processing space and stably generate a plasma inside the processing space.